Mario Kart DS Multiplayer problem.

I have a problem with Mario Kart on DS. I want to play with my DSi against my girl that has DSLite, but we are not able to do.
When we set a game, then we lose connection. We want to play with the Wi-Fi "near" mode.
All other games works perfectly in multiplayer. Maybe there is a patch for playing in multiplayer?
I have the European version of Mario Kart DS downloaded from this site.

Are you using DS Download Play? What Flashcart are you using?

It works fine for me on my R4 and on my AK2i, on my DS and my DSi. But I use the (U) version, and that may be the cause of it, or you flashcart. That too.

I have Acekard 2i with Akaio 1.5.1 and all updates loaders/plugins. My girl has R4 updated.

Is the R4 cart a legit one, or a clone? What firmware is on it?

actually, mine is the same. well... all games
i got a acekard 2i, 8gb kingston with dsi all AKAIO 1.5.1 all loaders and plugins are updated, and my friend only has a dsi. thats all
when i play mario vs luigi ("new" super mario bros.) it say that the communications are disconnected. the weird part is ONLY bomberman seems to work perfectly.

Well, I don't run 1.5.1 I use 1.5, and I have no problems, maybe you can try going back to 1.5?

lol i would but i wont be able to use my cheats :'(

All my cheats work fine. Do you auto update the cheats or manual update?

manual
the gbatemp cheats its not updated yet december 8 still...
do i have to update with the acekard?

I do. Go to Start>Wifiupdate(its on the second page)